When I first tackled the chapter on Vascular Tissues, I knew xylem and phloem were essential—but the details felt blurry. I started by sketching cross-sections of stems and roots, labeling vessels, tracheids, sieve tubes, and companion cells until their arrangement stuck in my mind.
- Xylem vessels and tracheids conduct water and dissolved minerals upwards.
- Phloem sieve tubes, assisted by companion cells, transport sugars and amino acids from photosynthetic “source” leaves to “sink” tissues.
Drawing these tissues side by side helped me see why the xylem walls are thickened with lignin, whereas phloem cells remain alive to load and unload organic solutes.
Sample SPM Question
“Differentiate between the structure and function of xylem vessels and phloem sieve tubes.”
My approach: list features (dead vs. living cells; wall thickness; direction of flow), then tie each feature back to its transport role.
No comments:
Post a Comment